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| Study on the quantitative definition of blasting damage zone scope based on wave velocity field inversion |
| FU Shuaiyang1，2，LI Haibo1，2，WU Di1，2，WANG Ben1，2，LIU Liwang3，LI Xiaofeng1，2 |
| (1. State Key Laboratory of Geomechanics and Geotechnical Engineering，Institute of Rock and Soil Mechanics，Chinese Academy of Sciences，Wuhan，Hubei 430071，China；2. University of Chinese Academy of Sciences，Beijing 100049，China；3. School of Mechanical Engineering，Nanjing University of Science and Technology，Nanjing，Jiangsu 210094，China) |
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Abstract Determining the scope of the rock mass blasting damage zone is important for evaluating the stability of underground engineering surrounding rock under blasting and controlling bedrock damage under excavation. A method based on wave velocity field inversion was proposed to determine the rock blasting damage zone scope quantitatively. This method was based on multistencils fast marching methods(MSFM) and simultaneous iterative reconstructive technique(SIRT). The effectiveness of the proposed method was verified by comparing the inversed wave velocity field with the known one. Blasting and wave velocity measurement simulations were carried out on the self-developed finite-discrete element solver OpenFDEM. The waveform data were processed using a self-programmed post-processing program，and thus the post-blasting wave velocity field was reconstructed. Based on the relationship between the changing rate of wave velocity and the degree of rock mass damage in the current code，the areas with different wave velocity changing rates were compared with the areas of cracks. The scopes of the blasting damage zone with different damage degrees were quantified using the ratio of the equivalent radius to the blast hole radius. 10% and 15% of the wave velocity changing rate were used as the thresholds for defining slightly and completely damage of the rock mass，respectively. The ratio of the equivalent radius of the slightly damage zone and the damage zone to the radius of the blast hole is about 11.86 and 7.2，respectively. As the blast load increases，the shape of the damage zones with different damage degree becomes irregular and the equivalent radius increases. The study results are expected to provide a reference for determining the scope of the blasting damage zone in the field.
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